Machine tool



Dec. 29, 1964 B. vAUcHER 3,163,811

MACHINE Toor.

Filed Marh 8. 1961 Imran br f 'amn Vaucer- United States Patent O3,]l631l MACHlNE TL Benjamin Vaueher, Tramelan, Switzerland, assigner toKummer Freres SA. Fabrique de Machines, Tramelan, Switzerland, ajoinostoeir company Filed Mar. 8, 1963i, Ser. No. 94,231 Claimspriority, application Switzerland, Mar. 3l, 1%9,

3,619/60 2 Claims. (Cl. Eig-275) This invention relates to machine toolsand in particular to machine tools with a workpiece driving spindle suchas automatic lathes.

Numerous machine tools with a workpiece driving spindle, which are knownin the art, are provided with electric controlling means to control amain power plant either in a partly automatic or even in a whollyautomatic manner, with a controlling or cycling device, eithermcchanical or of another type, to control the machining operations ofthe machine tool according to a predetermined cycle, and with aworkpiece feeding device which is automatically actuated at the end ofeach machining cycle, to introduce a new workpiece into the grippingmeans provided on the spindle. These known machine tools are fullyeliicient as long as the workpieces to machine therewith are cylindricalsince the said automatic feeding device can introduce these cylindricalworkpieces into the gripping means of the spindle when the latter hasbeen stopped in any position about its axis.

With a workpiece having a shaped contour the gripping means of thespindle must, however, be provided with a correspondingly shaped lodgingto receive said workpiece and it is therefore usually no longer possibleto use an automatic workpiece feeding device in combination with amachine tool of the type indicated.

@ne object of the invention is accordingly to improve the machine toolsof said type so as to enable using an Aautomatic workpiece feedingdevice in combination therewith, even when the workpieces tov machinehave anirregularly shaped contour.

lt is also an object of the invention to provide a machine tool of thetype indicated with stopping and orienting means acting on the spindleto bring the latter in a position around its axis corresponding to thatof the workn pieces fed by the automatic feeding device.

Still another object of the invention is to provide a machine tool withmeans arranged for stopping the spindle in a predetermined positionaround its axis, thus enabling the introduction of a new shapedworkpiece into a correspondingly shaped lodging of the gripping means ofthe spindle by merely shifting said workpiece along the spindle axis.

Further objects of the invention will become apparent in the course ofthe following description.

One embodiment of the machine tool according to the invention isrepresented diagrammatically and by way of example in the annexeddrawings.

In the drawings:

The single figure is a partial perspective view of some mechanicalelements of the machine tool improved in accordance with the inventionand it simultaneously shows a part of the wiring diagram of anelectromagnetic device automatically controlling the operation of saidmachine tool.

The machine tool represented comprises a spindle 1 arranged in aheadstock frame (not shown) for rotation about its longitudinal axis. Atits front end this spindle ICS A ring member 9 preferably of brass ismounted on spindle l so that it can bev set in any desired positionaround the spindle. A screw lil enables reliably securing ring 9 on tospindle 1 in the position it has inst been Set. A small ferromagneticpiece ll, preferably of soft iron, is mounted on ring 9 in fixedrelationship thereto.

Piece ll will preferably be embedded in ring member but it can alsoadvantageously be set in a cutout of an outwardly extending peripheralrim portion of member 9. Since piece ll is located in an eccentricposition with respect to spindle 1, it revolves around the spindle axiswhen the latter is rotating. During that motion, piece 1l thus travelsalong a circular path coaxial to spindle 1. By rotating member 9 aroundspindle l, the ferromagnetic piece l1 can be set in any desired positiontherearound, thus determining with precision, as disclosed hereinafter,the position in which the spindle will have to be stopped to permit aquite conventional automatic loading or feeding device (not shown) ofintroducing a shaped workpiece such as shown at 4l into thecorrespondingly shaped lodging of chuck 3 by merely shifting saidworkpiece along the spindle axis.

An electromagnet 13 and a vacuum-break magnetic Pole l5 and contact ldform part of a magnetic cir-y cuit, when magnet 13 isenergized, saidcircuit being closed and producing an attraction of contact i6,thus'opening switch le, upon arrival of piece l1 between the pole l5 andcontact 16. The magnet 13 and the switch ld themselves form part of anelectric control device which will now be described in detail.

rlfhis control device is fed by a three-phase alternating currentsupplied at terminals RST. It comprises at iirst a main circuit feedingmotor 5 with direct current through a rectier 2d when the contacts d2,d3, d4 are closed. When motor 5 is energized by this main circuit, itrotates at high speed thus enabling machining operations of the tools onthe workpiece Il,

The electric control device represented also comprises an auxiliarycircuit to drive the motor 5 at low speed when the spindle l. has to beoriented and stopped in kits loading position. This motor feedingauxiliary circuit is insered between the mains connected to terminals RTand it comprises the contacts c3, c4, b5, b5 and the variable resistorsR2.

It will be observed that this auxiliary circuit also feeds motor 5through rectifier Ztl. When said auxiliary circuit is energized, thereare, however, only two of the three sections of rectifier 2li 'which areoperative. The motor 5 is therefore running at a speed substantiallysmaller than when it is fed by its main circuit.

The electric control device of the machine tool improved according tothe invention further comprises a raking circuit connected in serieswith motor 5 and comprising contacts c5, d5, a resistor R1, and the coilof a relay A. This relay A forms part of means controlling the operationof Vthe dilerent circuits described above, said controlling means beingfed from a derivation of the mains connected to terminals ST through atranstormer lll, and said controlling means further comprising threerelays B, C, D, an auxiliary rectifier 2l to energize magnet 13, a mainswitch i7 and a starting switch 13.

The electric control device described functions as follows:

As soon as a workpiece d has been fed to chuck 3, the starting switch 18is closed, thus causing the motor 5 to be driven at high speed formachining said workpiece. The switch 18 could be closed manually, if theworkpiece were fed by hand, but it will preferably be actuatedautomatically by the mechanic cycling means of the machine controllingthe machining operations thereof in the conventional manner, saidcycling means accordingly comprising for instance a cam to close switch18 as soon as a new workpiece has been fed to and gripped by chuck 3.

Closing switch 13 causes the controlling current supplied by transformer19 at a potential of 60 volts, to pass through the main switch 17, thecontacts a2 and b4 and switch 13, and to energize relay D, thus closingthe contacts d2, d3 and d4 of the motor feeding main circuit. As alreadydescribed above, the direct current supplied then by rectifier 2t)causes the motor 5 to rotate at high speed. .The auxiliary contact d1 ofrelay D, which has been closed upon energization of this relay,energizes itself relay C through contact b2. This relay C closes the twocontacts c3, c4 of the motor feeding auxiliary circuit. Since contactsb5, be are, however, open, said auxiliary circuit is not yet closed. Theenergization of relays D and C opens the contacts d5 and c5 and breaksaccordingly the braking circuit connected in series with motor S. Bymeans of the Contact c2 relay C further closes its upkeeping circuitthrough contact b2.

When the workpiece d has been fully machined, the

cycling means of the machine open switch 13 thus interrupting theenergizing current of relays D and C. The motor feeding main circuit isthus interrupted by the three contacts d2, d3 and d4. At the same timethe contacts d5 and c5 close the braking circuit of the motor, whichenergizes relay A. As long as direct current flows through the brakingcircuit, the relay A will remain energized, so that the contacts :z2 anda1 of this relay will be opened and closed, respectiveiy. Thecontrolling current of transformer 19 thus passes during braking throughthe contact all and energizes relay B. rEhe latter' closes its contactsb5 and be of the motor feeding auxiliary circuit. Since contacts 03 andc4 are open during braking, said auxiliary circuit does not yet becomeoperative.

Relay B remains energized by means of its upkeeping contact b1 boththrough contact c1 and throu gh the magnetic switch 14, which is alsoclosed. By means of its contact b4 relay B avoids any accidentalenergization of relay D, and consequently of the motor feeding maincircuit, which could occur upon an inopportuno closure of switch 18,thus preventing motor 5 from rotating at high speed before a newworkpiece has been fed. The opened contact b2 of relay E also avoidsaccidentally energizing relay D upon closure of starting switch 18.During the braking cycle relay B prepares energizing relay C through itsContact b3.

After motor 5 and spindle 1 have been braked, no current passes any morethrough the braking circuit so that relay A is released. Contact a2 thuscloses the energizing circuit of relay C through contact b3, which hasbeen closed during braking. Relay C itself closes the contacts c3 and c4while simultaneously opening Contact c5. Since the motor feedingauxiliary circuit is now operative through the closed contacts b5, beand c3, c4, it will ydrive the motor 5 at low speed as explained above.This low speed drive of motor 5 permits orienting spindle 1. At the sametime the transformer 19 feeds the auxiliary rectifier 21`through switch16, contacts bi, c6 and potentiometer R3, thus energizing magnet 13. Thelatter is thus energized only when spindle 1 is actually driven at lowspeed. Any useless actuation of the vacuum-break `magnetic switch 1dwill therefore be avoided. The latter remains operative only during arelatively short period, after each machining cycle, so that it is notsubjected to a great wear. The potentiometer R3, connected to the saisirenergizing circuit of magnet 13, permits adjusting the potentialsupplied to said magnet.

When the ferromagnetic piece 11 comes between pole 15 of magnet 13 andcontact 16 of switch 14, this contact will be attracted and switch 14opened, thus breaking the energizing circuit of relay B. This relay thenopens contact b1 and interrupts its upkeeping circuit. Relay B alsoimmediately interrupts the energizing circuit of relay C by means of itscontact b3. Contacts c3 and c4 are accordingly opened and the auxiliaryfeeding circuit actuating motor 5 at low speed is also interrupted. Themotor braking circuit is at the same time closed again through contactsc5 and 5, so that the motor 5 is subjected to a short braking actionwhich will stop spindle 1 while piece 11 is still between pole 15 andcontact 16. This braking action is however very small and thecorresponding current passing in the braking circuit does not energizerelay A so that contacts a1 and a2 thereof remain in the positionrepresented in the drawings.

A cam (not shown) belonging to the mechanic cycling means controllingthe operation of the whole machine tool can now actuate the feedingdevice thereof to load a new workpiece into the shaped lodging of chuck3, thus preparing the machine for a new operating cycle. It will beobserved that the time eiapsing between the actuation by said cyclingmeans of starting switch 18 and that of the feeding device loading a newworkpiece to spindle 1 has to he chosen long enough to enable theelectric control device of the machine to brake the spindle and toorient the same in the loading position.

The electric control device described hereabove has the followingadvantages:

(l) After having machined a workpiece the motor 5 driving spindle 1 isbraked until it is almost stopped.

(2) As soon as spindle 1 has been stopped, a set of relays starts anorienting cycle by closing an auxiliary circuit driving motor 5 at lowspeed.

(3) An electromagnetic device becomes operative upon the passage of aferromagnetic piece 11 fixed to the spindle and stops the low speedmotion both of motor 5' and spindle 1.

(4) The position of piece 11 can be set around spindle 1 in any desiredposition, so as to stop the latter in any predetermined position aroundits axis.

(5) The spindle orienting means are arranged so as to prevent motor 5from rotating at high speed before spindle 1 has been oriented.

(6) The speed of spindle 1 during orienting can easily be adjusted atany desired value.

(7) During machining a workpiece the device controlling the low speedmotion of spindle 1 is completely deenergized so that the variousmembers actuated by said device are neither subjected to strains norwear.

Various modifications of the embodiment described abovev will becomeapparent to those skilled in the art, The direct current motor 5 could,for instance, be replaced by a three-phase current motor, its drive atlow speed being then ensured by a low frequency oscillating circuit, forinstance a circuit oscillating at a frequency substantially equal to 1Hz.

Although one particular embodiment of my invention has been describedabove with reference to the drawings, it should be understood that I donot wish to be limited to the details thereof except as defined by theappended claims.

I claim:

1. A power control stop for a rotatable spindle arranged for rotationabout an axis, a direct current motor to drive said spindle andelectromagnetic means comprising a ferromagnetic piece fixed on theperiphery of said spindle and revolving therearound along apredetermined circular path when said spindle is rotating, a fixedelectromagnet having a pole extending on one side of said circularpredetermined path and spaced adjacent thereto, a iixed magnetic controlswitch having a movable Contact facing said pole of the electromagnetand extending on the opposite side of and in alignment with said pole, amotor feeding main circuit to cause said motor to rotate `at high speed,a motor feeding auxiliary circuit to cause said motor to rotate at aconstant low speed, a braking circuit to brake said motor, andcontrolling means energized by said braking circuit to switch offimmediately said motor feeding main circuit, to switch on said motorfeeding auxiliary circuit after said braking circuit has braked saidmotor and to energize said electromagnet, said magnetic switch switchingoff said motor feeding auxiliary circuit upon arrival of saidferromagnetic piece between said movable contact of the magnetic switchand said pole 0f the electromagnet, when the latter is energized.

2. A power control stop according to claim 1, wherein said brakingcircuit is provided With a resistor, said resistor being connected inparallel to the terminals of said direct current motor when said brakingcircuit is switched on, said controlling means being energized by thevoltage drop across said resistor.

References Cited by the Examiner UNITED STATES PATENTS 2,191,137 2/40Trible 82-28 2,338,975 1/44 Schumacher 82--28 2,753,502 7/56 Kylin318-26 3,017,555 1/62 Newman et al. S18-380 FOREIGN PATENTS 147,54811/54 Sweden.

ORIS L. RADER, Primary Examiner.

RICHARD H. EANES, JR., Examiner.

1. A POWER CONTROL STOP FOR A ROTATABLE SPINDLE ARRANGED FOR ROTATIONABOUT AN AXIS, A DIRECT CURRENT MOTOR TO DRIVE SAID SPINDLE ANDELECTROMAGNETIC MEANS COMPRISING A FERROMAGNETIC PIECE FIXED ON THEPERIPHERY OF SAID SPINDLE AND REVOLVING THEREAROUND ALONG APREDETERMINED CIRCULAR PATH WHEN SAID SPINDLE IS ROTAING, A FIXEDELECTROMAGNET HAVING A POLE EXTENDING ON ONE SIDE OF SAID CIRCULARPREDETERMINED PATH AND SPACED ADJACENT THERETO, A FIXED MAGNETIC CONTROLSWITCH HAVING A MOVABLE CONTACT FACING SAID POLE OF THE ELCTROMAGNET ANDEXTENDING ON THE OPPOSITE SIDE OF AND IN ALIGNMENT WITH SAID POLE, AMOTOR FEEDING MAIN CIRCUIT TO CAUSE SAID MOTOR TO ROTATE AT HIGH SPEED,A MOTOR FEEDING AUXILIARY CIRCUIT TO CAUSE SAID MOTOR TO ROTATE AT ACONSTANT LOW SPEED, A BRAKING CIRCUIT TO BRAKE SAID MOTOR, ANDCONTROLLING MEANS ENERGIZED BY SAID BRAKING CIRCUIT TO SWITCH OFFIMMEDIATELY SAID MOTOR FEEDING MAIN CIRCUIT, TO SWITCH ON SAID MOTORFEEDING AUXILIARY CIRCUIT AFTER SAID BRAKING CIRCUIT HAS BRAKED SAIDMOTOR AND TO ENERGIZE SAID ELECTROMAGNET, SAID MAGNETIC SWITCH SWITCHINGOFF SAID MOTOR FEEDING AUXILIARY CIRCUIT UPON ARRIVAL OF SAIDFERROMAGNETIC PIECE BETWEEN SAID MOVABLE CONTACT OF THE MAGNETIC SWITCHAND SAID POLE OF THE ELCTROMAGNET, WHEN THE LATTER IS ENERGIZED.